Characterization, nanostructure, and transport properties of styrene grafted PVA/SiO2 hybrid nanocomposite membranes: Positron lifetime study

Gamma radiation-induced graft copolymerization of styrene monomer on a polyvinyl alcohol film has successfully prepared a proton exchange membrane based on polyvinyl alcohol/silicon nanoparticles (PVA/SiO2), for use in fuel cells. The physical and chemical properties of the prepared hybrid nanocomposite membranes were examined by the Fourier transformer infrared spectrometer (FTIR) and the hardness test. The electrochemical properties were studied as a function of the degree of grafting at different doses of gamma irradiation. Ion exchange capacity (IEC) was found to improve with rising in the degree of grafting and then slightly decrease because of styrene homo-polymerizes as the dose of gamma irradiation intensifies. As the graft grade increases, the proton's conductivity rises to 30% of the degree of grafting and then begins to stabilize. The free volume hole size obtained from positron annihilation lifetime (PAL) experiments was found to increase by the further accumulation of the styrene graft content. The results of PAL support electrochemical results. Also, a strong link between the results of nanoscopic properties from PAL, and the results of chemical and physical properties (macroscopic results) has been successfully established. The prepared PVA/SiO2-grafted sulfonated styrene seems to be a potential alternative to Nafion for fuel cell applications.

Automated summary

The study successfully prepared a proton exchange membrane based on PVA/SiO2, and investigated the physical, chemical, and electrochemical properties. It was found that ion exchange capacity and proton conductivity improved with increasing degree of grafting, while positron annihilation lifetime experiments revealed changes in free volume hole size with accumulation of styrene graft content. The results of the nanoscopic properties from PAL experiments were successfully linked to the chemical and physical properties, demonstrating the potential of the prepared PVA/SiO2-grafted sulfonated styrene for fuel cell applications as an alternative to Nafion.